1. Field of the Invention
The invention relates to a lighting method and a lighting apparatus having a variable illuminated field, in particular for operating-rooms.
2. Description of the Prior Art
Surgical operations call for high-intensity lighting systems which satisfy certain functional criteria. The illuminated field must have uniform lighting but must not have a sharp contour in order to avoid lighting boundaries which produce disagreeable contrasts for the surgeon's eye.
Some operating-room lighting systems project a light source on zones having fixed dimensions of contours and constant illumination. These zones can be displaced and superimposed in order to vary the level of illumination of the field under observation.
U.S. Pat. No. 4.745.526, the disclosure of which is considered as incorporated in the present disclosure, is directed to such known lighting systems.
One object of the invention is to propose a lighting system for producing at a predetermined distance from an operating-room lighting lamp an illuminated field which is variable both in dimensions and in illumination.